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Wednesday, 14 December 2011

Civil 3D Performance Part I - Memory Management and Your Operating System

In my Autodesk University class, I talked about operating systems and which one was best for AutoCAD Civil 3D. Of course we all know that the ultimate answer is “Windows 7 x64.” It just makes sense. But during a luncheon, I had a customer tell me “You know, common sense told me that Windows 7 x64 was the right operating system to use, but you really simplified it and told me why it was the right one.” I’d like to share with you why Windows 7 x64 is the best operating system to use for AutoCAD Civil 3D as well…find out the secret after the jump (teaser – I’ll be showing the infamous “school bus” graphic if you click the link to see the rest of the post!)

The answer is all about memory management. Forget for a bit that you can access more memory with a 64 bit operating system – that’s not really important to this particular conversation. Memory management, however, is.

In past operating systems, you’ve likely ran the Disk Defrag command. This command rearranged the data on your disk to arrange it in a more orderly fashion, which made it more efficient to search for. Those large, continuous areas of free (white) space made thing efficient.

Not surprisingly, free space is important in memory management as well – and here’s where the operating system comes into play. Back in the Windows XP days, memory management was sporadic at best – when a software program sent a memory request, it just fell into any spot that it wanted to. This is illustrated in the following graphic:

In the top part of the graphic, you have a long bit of free address space. In the bottom part of the graphic, a software program makes a memory request and it just falls into the middle of the free space. This splits up the free block into two much smaller free blocks, leaving less room for future memory requests. When a large memory request comes in, it can’t find enough free space and the program invariably crashes. This is why you can run out of system memory on a 32 bit system even when the Task Manager shows that you have “X” amount of free memory available – it’s not the available memory that’s important, it’s the amount of contiguous free memory that’s important.

So here it is – one of my famous analogies – in the following example, we have the AutoCAD Civil 3D Memory Bus. Driving this particular bus is our good friend Windows XP x32. Now Windows XP is one lazy bus driver – probably looking forward to retirement. He doesn’t care where people sit, as long as they sit. This causes a problem, as you can see below:

First, we pick up some AutoCAD riders (memory requests.) Instead of sitting together, they sit wherever they want to, leaving a smaller space for future riders.

Next, we pick up some Map 3D riders – like the annoying AutoCAD riders, they split up, leaving just one tiny seat in the middle for Civil 3D riders (and those tend to be much larger riders…)

Where does the big Civil 3D guy sit?

Had Windows 7 x64 been driving this bus, he would have been much more diligent about seating – those AutoCAD kids would have to sit together, as would the Map 3D guys, leaving much more room for our Civil 3D buddy to spread out and be comfortable – this is important, because a Civil 3D rider who won’t fit into an available seat can cause the whole bus to crash and go up in a flaming pile of twisted metal!

Hopefully this helps explain memory management and why it’s so important – stay tuned for more posts that explain things you can do improve performance with AutoCAD Civil 3D!

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Civil 3D Performance Part I - Memory Management and Your Operating System

In my Autodesk University class, I talked about operating systems and which one was best for AutoCAD Civil 3D. Of course we all know that the ultimate answer is “Windows 7 x64.” It just makes sense. But during a luncheon, I had a customer tell me “You know, common sense told me that Windows 7 x64 was the right operating system to use, but you really simplified it and told me why it was the right one.” I’d like to share with you why Windows 7 x64 is the best operating system to use for AutoCAD Civil 3D as well…find out the secret after the jump (teaser – I’ll be showing the infamous “school bus” graphic if you click the link to see the rest of the post!)